Internal voltage generation circuit

ABSTRACT

An internal voltage generation circuit includes a driving control signal generation unit configured to receive a temperature signal enabled when the internal temperature is below a preset temperature and generate first and second driving control signals, and an internal voltage generation unit configured to receive the first and second driving control signals and generate an internal voltage.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 12/459,363, filed Jun. 29, 2009, now U.S. Pat. No. 8,050,112claiming priority of Korean Application No. 10-2008-0097388, filed Oct.2, 2008, the entire contents of which are incorporated herein byreference

TECHNICAL FIELD

This disclosure relates to a semiconductor memory device, and moreparticularly, to an internal voltage generation circuit capable ofincreasing an internal voltage driving force according to a temperature.

BACKGROUND

In general, a memory device receives a power voltage (VDD) and a groundvoltage (VSS) from the outside, and generates and uses an internalvoltage required for internal operation. A voltage required for internaloperation of the semiconductor memory device includes an internal power(VCORE) supplied to a memory core region, a high voltage (Vpp) used upondriving of a word line or overdriving and a back bias voltage (VBB)supplied as a bulk voltage of an NMOS transistor in the core region.

Also, the internal voltage includes a cell plate voltage (VCP) used as aplate voltage of a memory cell capacitor and a bit line prechargevoltage (VBLP) used to precharge a bit line. In general, the cell platevoltage (VCP) and the bit line precharge voltage (VBLP) are generatedfrom the internal power (VCORE) and are generated to a half level of theinternal power (VCORE) to minimize current consumption.

FIG. 1 is a circuit diagram illustrating a conventional internal voltagegeneration circuit.

As illustrated, the conventional internal voltage generation circuit isa circuit for generating a cell plate voltage VCP or a bit lineprecharge voltage VBLP, and voltage-divides the internal power VCOREthrough a plurality of resistance elements R10-R13 and drives theinternal voltage VCP/VBLP by comparing a level of a voltage of a nodend10 generated to a half level of the internal power VCORE and a levelof the internal voltage VCP/VBLP.

Operation of the internal voltage generation circuit illustrated in FIG.1 will be described in more detail.

Levels of pull-up driving signal PDRV and pull-down driving signal NDRVare regularly maintained when the level of the internal voltage VCP/VBLPis the half level of the internal power VCORE, i.e., there is novariation, the internal voltage VCP/VBLP is driven by a regular currentand is maintained at a regular level.

In this state, if the level of the internal voltage VCP/VBLP is loweredbelow the voltage of the node nd10, the levels of the pull-up drivingsignal PDRV and the pull-down driving signal NDRV are graduallydecreased and a turn-on degree of a PMOS transistor P16 becomes largerthan a turn-on degree of an NMOS transistor N18. Accordingly, the levelof the internal voltage VCP/VBLP is increased. Also, if the level of theinternal voltage VCP/VBLP is raised above the voltage of the node nd10,the levels of the pull-up driving signal PDRV and the pull-down drivingsignal NDRV are gradually increased and the turn-on degree of the NMOStransistor N18 becomes larger than the turn-on degree of the PMOStransistor P16. Accordingly, to the level of the internal voltageVCP/VBLP is decreased. In other words, the internal voltage generationcircuit controls so that the level of the internal voltage VCP/VBLP isgenerated to a half level of the internal power VCORE.

However, in the conventional internal voltage generation circuit of FIG.1, a driving force for driving the internal voltage VCP/VBLP isconsiderably decreased at a low temperature as compared to a hightemperature.

Referring to FIG. 2, currents for driving the internal voltage VCP/VBLP(hereinafter, referred to as ‘driving current’) at a high temperature(90° C.) and a low temperature (−40° C.) when the internal voltageVCP/VBLP is varied from 0.4 V to 0.8 V are compared. That is, at a hightemperature (90° C.), the driving current is 1.1 mA if the internalvoltage VCP/VBLP is lowered to 0.5 V and the driving current is 2.6 mAif the internal voltage VCP/VBLP is raised to 0.7 V. On the other hand,at a low temperature (−40° C.), the driving current is 0.24 mA if theinternal voltage VCP/VBLP is lowered to 0.5 V and the driving current is−0.3 mA if the internal voltage VCP/VBLP is raised to 0.7 V. Here, thedriving current is the current supplied through the PMOS transistor P16and the NMOS transistor N18 to drive the internal voltage VCP/VBLP. Thepositive (+) driving current means that the internal voltage VCP/VBLP ispulled up as the current supplied through the PMOS transistor P16 islarger than the current discharged through the NMOS transistor N18, andthe negative (−) driving current means that the internal voltageVCP/VBLP is pulled down as the current supplied through the PMOStransistor P16 is smaller than the current discharged through the NMOStransistor N18.

As such, since the driving current is considerably decreased at a lowtemperature (−40° C.) as compared to a high temperature (90° C.), ittakes too much time to reset the internal voltage VCP/VBLP with a variedlevel to a half level of the internal voltage VCORE.

BRIEF SUMMARY

In an aspect of this disclosure, there is provided an internal voltagegeneration circuit capable of reducing a time taken to reset theinternal voltage VCP/VBLP with a varied level to a predetermined levelby increasing a driving current at a low temperature.

In an embodiment, an internal voltage generation circuit includes adriving control signal generation unit configured to receive atemperature signal enabled when the internal temperature is below apreset temperature and generate first and second driving controlsignals, and an internal voltage generation unit configured to receivethe first and second driving control signals and generate an internalvoltage.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages will be moreclearly understood from the following detailed description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a circuit diagram illustrating a conventional internal voltagegeneration circuit;

FIG. 2 is a view illustrating variation in a driving current withvariation in an internal voltage at different temperatures;

FIG. 3 is a block diagram illustrating a configuration of an internalvoltage generation circuit in accordance with an embodiment of thepresent invention;

FIG. 4 is a circuit diagram illustrating a temperature detection unitincluded in the internal voltage generation circuit of FIG. 3;

FIG. 5 is a timing diagram illustrating operation of the temperaturedetection unit of FIG. 4;

FIG. 6 is a circuit diagram illustrating a driving control signalgeneration unit included in the internal voltage generation circuit ofFIG. 3;

FIG. 7 is circuit diagram illustrating an internal voltage generationunit included in the internal voltage generation circuit of FIG. 3; and

FIG. 8 is a view illustrating variation in a driving current withvariation in an internal voltage at different temperatures.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to accompanying drawings. However, the embodiments are forillustrative purposes only and are not intend to limit the scope of theinvention.

FIG. 3 is a block diagram illustrating a configuration of an internalvoltage generation circuit in accordance with an embodiment of thepresent invention.

The internal voltage generation circuit as illustrated in FIG. 3includes a temperature detection unit 2, a driving control signalgeneration unit 3 and an internal voltage generation unit 4.

The temperature detection unit 2 includes, as illustrated in FIG. 4, avoltage dividing unit 20, a level setting unit 23 and a buffer unit 26.The voltage dividing unit 20 includes a first resistor unit 21consisting of resistance elements R20, R21 serially connected between aninternal power VCORE and a node nd20 and a second resistor unit 22consisting of NMOS transistors N20-N23 serially connected between thenode nd20 and a ground voltage VSS. The level setting unit 23 includes apull-up unit 24 which consists of PMOS transistors P20, P21 seriallyconnected between the internal power VCORE and a node nd21 and pulls upthe node nd21 in response to a signal of the node nd20, a pull-down unit25 which consists of NMOS transistors N24-N26 serially connected betweenthe node nd21 and the ground voltage VSS and an inverter IV20 whichinverts the signal of the node nd21 and outputs an inverted signal tonode nd22. The buffer unit 26 consists of inverters IV21, IV22, andbuffers a signal of the node nd22 and generates a temperature signalTEMP.

The temperature detection unit 2 generates the temperature signal TEMPof a high level when an internal temperature of the semiconductor memorydevice is below a preset temperature, and generates the temperaturesignal TEMP of a low level when the internal temperature exceeds thepreset temperature.

Describing operation of the temperature detection unit 2 morespecifically with reference to FIG. 5, when the temperature is increasesfrom −40° C. to 120° C., a resistance of the first resistor unit 21consisting of resistance elements R20, R21 is increased and a resistanceof the second resistor unit 22 consisting of NMOS transistors N20-N23 isdecreased. Accordingly, the level of the node nd20 is decreased sincethe current discharged through the second resistor. unit 22 is larger.The level of the node nd20 is converted to a digital level through thelevel setting unit 23 and outputted to the node nd22, and the level ofthe node nd22 is shifted from a high level to a low level in a periodwhere the internal temperature is 0° C. Therefore, the temperaturedetection unit 2 generates the temperature signal TEMP, a level of whichis shifted on the basis of the internal temperature of 0° C. In otherwords, the temperature signal TEMP generated in the temperaturedetection unit 2 is a high level when the internal temperature is below0° C. and a low level when the internal temperature is more than 0° C.

The driving signal generation unit 3 includes, as illustrated in FIG. 6,a first transfer unit 30 and a second transfer unit 32. The firsttransfer unit 30 includes a first transfer gate T30 transferring theinternal power VCORE to a first driving control signal PDRVT in responseto the temperature signal TEMP, and a second transfer gate T31transferring a first driving signal PDRV to the first driving controlsignal PDRVT in response to the temperature signal TEMP. The secondtransfer unit 32 includes a third transfer gate T32 transferring theground voltage VSS to a second driving control signal NDRVT in responseto the temperature signal TEMP and a fourth transfer gate T33transferring a second driving signal NDRV to the second driving controlsignal NDRVT in response to the temperature signal TEMP.

In the driving control signal generation unit 3 having the configurationas described above, the second transfer gate T31 and the fourth transfergate T33 are turned on and the first driving signal PDRV is transferredto the first driving control signal PDRVT and the second driving signalNDRV is transferred to the second driving control signal NDRVT when thetemperature signal TEMP is at a high level, i.e., the internaltemperature is below 0° C. Meanwhile, the first transfer gate T30 andthe third transfer gate T32 are turned on and the internal power VCOREis transferred to the first driving control signal PDRVT and the groundvoltage VSS is transferred to the second driving control signal NDRVTwhen the temperature signal TEMP is at a high level, i.e., the internaltemperature exceeds 0° C.

The internal voltage generation unit 4 includes, as illustrated in FIG.7, a level signal generation unit 40, a control voltage generation unit42, a driving signal generation unit 44, a driving unit 46 and a drivingcontrol unit 48.

The level signal generation unit 40 voltage-divides the internal powerVCORE and generates a level signal LEV. At this time, sum of resistancesof the resistance element R40 and the resistance element R41 and sum ofresistances of the resistance element R42 and the resistance element R43are set equal to each other, and the level signal LEV is thus set to ahalf level of the internal power VCORE.

The control voltage generation unit 42 includes PMOS transistors P40,P41 and NMOS transistors N40-N43 forming a current mirror, and receivesthe level signal LEV and generates a first control voltage PBV forcontrolling current supplied from the internal power VCORE and a secondcontrol voltage NBV for controlling current discharged to the groundvoltage VSS.

The driving signal generation unit 44 includes PMOS transistors P42, P43turned on in response to the first control voltage PBV, NMOS transistorsN46, N47 turned on in response to the second control voltage NBV, andPMOS transistors P44, P45 and NMOS transistors N44, N45 comparing levelsof the level signal LEV and the internal voltage VCP/VBLP and generatingthe first driving signal PDRV and the second driving signal NDRV. Levelsof the first driving signal PDRV and the second driving signal NDRVgenerated in the driving signal generation unit 44 are decreased whenthe level of the internal voltage VCP/VBLP becomes smaller than that ofthe level signal LEV, and are increased when the level of the internalvoltage VCP/VBLP becomes larger than that of the level signal LEV.

The driving unit 46 includes a PMOS transistor P46 which is a pull-updevice pulling up the internal voltage VCP/VBLP in response to the firstdriving signal PDRV, and an NMOS transistor N48 which is a pull-downdevice pulling down the internal voltage VCP/VBLP in response to thesecond driving signal NDRV. When the level of the internal voltageVCP/VBLP becomes smaller than that of the level signal LEV, a turn-ondegree of the PMOS transistor P46 becomes larger than a turn-on degreeof the NMOS transistor P48 since the levels of the first driving signalPDRV and the second driving signal NDRV are reduced, and the level ofthe internal voltage VCP/VBLP is thus increased. On the other hand, whenthe level of the internal voltage VCP/VBLP becomes larger than that ofthe level signal LEV, the turn-on degree of the NMOS transistor P48becomes larger than the turn-on degree of the PMOS transistor P46 sincethe levels of the first driving signal PDRV and the second drivingsignal NDRV are increased, and the level of the internal voltageVCP/VBLP is thus reduced.

The driving control unit 48 includes a PMOS transistor P47 which is apull-up device pulling up the internal voltage VCP/VBLP in response tothe first driving control signal PDRVT, and an NMOS transistor N49 whichis a pull-down device pulling down the internal voltage VCP/VBLP inresponse to the second driving control signal NDRVT. When the internaltemperature of a semiconductor memory device is below 0° C., the drivingcontrol unit 48 is driven in similar manner as the driving unit 46 sincethe first and second driving control signals PDRVT and NDRVT become thesame level as the first and second driving signals PDRV and NDRV,respectively, in response to the temperature signal TEMP of a highlevel. Therefore, when the internal temperature of a semiconductormemory device is below 0° C., the internal voltage VCP/VBLP is drivennot only by the driving unit 46 but also by the driving control unit 48.Accordingly, the driving current driving the internal voltage VCP/VBLPis increased. On the other hand, when the internal temperature of asemiconductor memory device exceeds 0° C., the driving control unit 48is not driven since the first and second driving control signals PDRVTand NDRVT become the same level as the internal power VCORE and theground voltage VSS, respectively, in response to the temperature signalTEMP of a low level. Therefore, when the internal temperature of asemiconductor memory device exceeds 0° C., the internal voltage VCP/VBLPis driven only by the driving unit 46.

In brief description, the internal voltage generation circuit inaccordance with an embodiment of the present invention drives theinternal voltage VCP/VBLP only by the driving unit 46 when the internaltemperature exceeds 0° C., and drives the internal voltage VCP/VBLP notonly by the driving unit 46 but also by the driving control unit 48 whenthe internal temperature is below 0° C. As described above, the internalvoltage generation circuit in accordance with an embodiment of thepresent invention shortens the time taken to reset the internal voltageVCP/VBLP with a varied level to the half level of the internal powerVCORE by increasing the driving current for driving the internal voltageVCP/VBLP at a low temperature.

Referring to FIG. 8, variations in the driving current for driving theinternal voltage VCP/VBLP at a high temperature (90° C.) and a lowtemperature (−40° C.) when the internal voltage VCP/VBLP is varied from0.4 V to 0.8 V are compared. At a high temperature (90° C.), the drivingcurrent is 1.1 mA if the internal voltage VCP/VBLP is lowered to 0.5 Vand the driving current is 2.6 mA if the internal voltage VCP/VBLP israised to 0.7 V. This is the same as the conventional art. On the otherhand, at a low temperature (−40° C.), the driving current is 0.73 mA ifthe internal voltage VCP/VBLP is lowered to 0.5 V and the drivingcurrent is −1.0 mA if the internal voltage VCP/VBLP is raised to 0.7 V.From this result, it can be appreciated that the driving current isconsiderably increased at a low temperature as compared to theconventional art.

The internal voltage generation circuit in accordance with an embodimentof the present invention adjusts the driving current driving theinternal voltage VCP/VBLP on the basis of a temperature of 0° C. That isto say, internal voltage generation circuit in accordance with anembodiment of the present invention increases the driving currentdriving the internal voltage VCP/VBLP when the internal temperature ofthe semiconductor memory device is below 0° C. At this time, the basetemperature of 0° C. can be variously set if necessary.

While the present invention has been described with respect to thespecific embodiments and examples, it will be apparent to those skilledin the art that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention as defined in thefollowing claims.

1. An internal voltage generation circuit, comprising: a driving controlsignal generation unit configured to receive a temperature signalenabled when the internal temperature is below a preset temperature andgenerate first and second driving control signals; and an internalvoltage generation unit configured to receive the first and seconddriving control signals and generate an internal voltage.
 2. Theinternal voltage generation circuit of claim 1, wherein the drivingcontrol signal generation unit includes: a first transfer unitconfigured to selectively output an internal power or a first drivingsignal to the first driving control signal in response to thetemperature signal; and a second transfer unit configured to selectivelyoutput a ground voltage power or a second driving signal to the seconddriving control signal in response to the temperature signal.
 3. Theinternal voltage generation circuit of claim 2, wherein the firsttransfer unit includes: a first transfer device configured to transferthe internal power to the first driving control signal in response tothe temperature signal; and a second transfer device configured totransfer the first driving signal to the first driving control signal inresponse to the temperature signal.
 4. The internal voltage generationcircuit of claim 2, wherein the second transfer unit includes: a firsttransfer device configured to transfer the ground voltage to the seconddriving control signal in response to the temperature signal; and asecond transfer device configured to transfer the second driving signalto the second driving control signal in response to the temperaturesignal.
 5. The internal voltage generation circuit of claim 1, whereinthe internal voltage generation unit includes: a level signal generationunit configured to voltage-divide an internal power and generate a levelsignal; a control voltage generation unit configured to receive thelevel signal and generate first and second control voltages; a drivingsignal generation unit configured to receive the first and secondcontrol voltages and generate first and second driving signals; adriving unit configured to receive the first and second driving signalsand drive the internal voltage; and a driving control unit configured toreceive the first and second driving control signals and drive theinternal voltage.
 6. The internal voltage generation circuit of claim 5,wherein the driving control unit includes: a pull-up device which isconnected between the internal power and an output terminal of theinternal voltage and pulls up the internal voltage in response to thefirst driving control signal; and a pull-down device which is connectedbetween the output terminal of the internal voltage and a ground voltageand pulls down the internal voltage in response to the second drivingcontrol signal.